1. Field of the Invention
This invention discloses the formulation and use of an advanced solid-media chemical composition designed and intended to enhance the removal of a broad range of environmental contaminants, including petroleum hydrocarbons and low molecular weight halogenated organic compounds, from industrial wastes, soils, sediments, sludges, ground waters, surface waters, and the like. In particular, this invention provides an improved means of promoting the chemical oxidation and aerobic, biologically mediated degradation, transformation, and/or detoxification of a broad range of organic contaminants in the environment, including, but not limited to, petroleum products such as gasoline, diesel fuel, fuel oils, and lubricating oils and halogenated organic solvents such as perchloroethylene, trichloroethylene, trichloroethane, and freon. Either alone or in combination with other liquid and solid-chemical compositions, the present invention also has the potential for the remediation of MTBE. This invention provides improved means for: (i) providing for a sustained release of active oxygen, (ii) creating, enhancing, and maintaining aerobic conditions (i.e., high-dissolved oxygen and positive Eh values), (iii) providing a source of co-substrates and nutrients to promote the growth of contaminant-degrading microorganisms, and (iv) providing sources of inoculum of beneficial microorganisms which act to promote the biodegradation of contaminants. This invention specifically reveals an improved, solid-chemical composition and related methods which are designed to provide the combined benefits of relatively long-term, low-temperature chemical-oxidation processes, (akin to a gentler or less-aggressive Fenton reaction), as well as the enhancement of aerobic biological processes which work together to promote the biodegradation, transformation, and/or detoxification of the aforementioned environmental contaminants.
2. Description of Prior Art
Soil and ground-water pollution caused by chemical contaminants released into the environment is a well documented, world-wide problem. Such chemical contamination is associated with many different types of industrial activities over the last two centuries. Common environmental contaminants include several different types and forms of petroleum hydrocarbons and halogenated organic compounds including solvents (e.g., tetra- and trichloroethene, methylene chloride). The available toxicological data indicates that many of these contaminants, in particular many of the halogenated organic compounds, are either carcinogenic or potentially carcinogenic to both man and animals. In addition, the available environmental and ecological data have shown that many of these contaminants tend to persist in the environment for long time periods. The long-term stability and extremely slow degradation of many such environmental contaminants presents a substantial, long-term hazard to human health and the environment throughout the industrialized world.
The disclosed invention relates to the use of oxygenation compounds, and mixtures of these oxygenation compounds with microbial co-substrates and nutrients, to foster both the chemical oxidation and aerobic bioremediation of petroleum hydrocarbons and low-molecular weight chlorinated organic solvents in soil and ground water.
Chemical-oxidation treatment of wastes generally involves the use of strong oxidizing agents such as hydrogen peroxide, ozone, potassium permanganate, and other agents to chemically transform and/or destroy organic wastes in liquid, particularly aqueous wastes. Many chemical-oxidation practices taught in the prior art involve the use of such oxidizers to chemically destroy or transform undesirable organic compounds, such as organic solvents in such waste streams. Chemical-oxidation reactions may also be used to oxidize inorganic compounds, such as the reduced forms of certain metals, into their oxidized forms. In theory and practice, the oxidizing agents generate highly reactive, short-lived species of oxygen, such as the hydroxyl radical (.OH), which subsequently oxidize the organic and inorganic compounds. The complete chemical-oxidation of organic compounds would in theory produce carbon dioxide and water as the ultimate end products. Chemical oxidation has been used to remediate organic contaminants in soil, ground-water, and industrial waste streams. Most of the prior art on this topic address applications of the “classic” chemical-oxidation reaction, the so-called Fenton reaction, which involves the use of Fenton's Reagent, i.e., ferrous iron (Fe2+). The ferrous iron serves as a catalyst for the chemical-oxidation of an organic substrate in the presence of the hydroxyl radical provided for by an oxidizing agent, such as hydrogen peroxide. The fundamental chemistry of the Fenton reaction has been known for approximately 100 years and the reagents used are readily available and relatively inexpensive. Unfortunately for in-situ environmental-remediation applications, chemical-oxidation reactions involving the use of strong oxidizers such as concentrated hydrogen peroxide or potassium permanganate are vigorous and exothermic, and can generate dangerous amounts of heat and toxic and potentially explosive fumes which necessitate the incorporation of significant health-and-safety precautions otherwise not be required for other in-situ technologies such as bioremediation. In fact, there was a recently documented case in Wisconsin whereby the heat generated by the in-situ injection of hydrogen peroxide produced vapors which actually exploded, causing extensive damage to the site.
Many of the so-called conventional methods for the remediation or clean-up of chemically contaminated wastes, waters, soils, and sediments have generally involved either the physical removal of the contaminated media or the simple mass transfer of the contaminants from one media (e.g., soil) to another (e.g., air). In general, such physical-treatment technologies do not involve the chemically and/or biologically mediated breakdown, transformation, or detoxification of the contaminants. Two of the most common categories of physical environmental remediation technologies are the excavation of contaminated soils and the pumping and subsequent treatment of contaminated ground water. The excavation of contaminated soils is often followed by their disposal in a landfill, which can pose a potential long-term risk to the environment. Many ground-water pump-and-treat processes involve the simple mass-transfer or “stripping” of the contaminants from the water into the air. Another common physical-treatment method involves the use of granular activated carbon (GAC) reactors to treat chemically contaminated waters. When contaminated water is passed through a GAC reactor, the contaminants are physically adsorbed onto the carbon particles, thereby producing another contaminated media which requires subsequent disposal and/or treatment. Each of these physical-treatment technologies shares the same disadvantage—i.e., they do not reduce the actual amount or toxicity of the chemical contaminants, but rather they simply involve the mass-transfer of the contaminants from one place or media to another.
Bioremediation involves the use of microorganisms, such as bacteria and fungi, to convert chemical compounds into innocuous or less harmful chemical compounds. Bioremediation technologies generally have lower costs associated with their use and implementation than do the competing physical technologies. Bioremediation technologies are also applicable to a broader range of contamination problems and variations in field conditions than physical-treatment technologies. Most bioremediation technologies also do not present significant health & safety issues such as those posed by the use of exothermic, Fenton-type chemical-oxidation reactions. Bioremediation processes may be aerobic, which require the addition of oxygen, or anaerobic, which do not require oxygen.
The most promising bioremediation technologies provide the additional capability of treating contaminated media in-situ, i.e., in place, without the need for ground-water pumping or soil excavation. Current trends in bioremediation technology indicate that the most technically feasible and commercially successful bioremediation technologies are those which utilize indigenous or “native” contaminant-degrading bacteria (CDB), fungi and other microorganisms which are naturally present in the contaminated media. The presence of CDB in many different types of environments has been extensively reported in the scientific literature. There is an extensive body of prior art literature and patents concerning various means of using both aerobic and anaerobic CDB (as well as engineered or cultured bacteria) to biodegrade organic contaminants in water, soil, and industrial wastes. An important requirement of bioremediation processes which use native or “added” aerobic microorganisms is to provide sufficient amounts of oxygen and nutrients to promote the growth of bacteria and other organisms that can degrade environmental contaminants. Hence, it may be important to add sources of oxygen and inorganic nutrient forms of nitrogen and phosphorus, which can be added through a variety of means to increase the activity of the native CDB population.
U.S. Pat. No. 3,796,637 to Fusey discloses the use of compositions containing from 10% to 40% by weight of a metal oxide (e.g., iron oxide, manganese dioxide, zinc oxide) and/or alkali metal peroxide (e.g., sodium peroxide, potassium peroxide) which promotes the biological degradation of hydrocarbon-containing waste materials. The use of oxygenating compounds leads to aerobic fermentation which reduces the nuisance odors associated with anaerobic fermentation. The compositions may also contain nutrient substances (e.g., corn liquor, malting wastes or residues, molasses) and/or nitrogen species (e.g., urea, ammonium phosphate, ammonium nitrate, ammonium sulfate). Fusey does not disclose the use of complex phosphate compounds which serve as both oxygen release moderators and supplemental nutrients for the native contaminant-degrading bacteria. Likewise, Fusey fails to address the role of the metallic peroxides as stimulating long-term, low-temperature chemical oxidation processes. Hence, Fusey does not disclose the present invention.
U.S. Pat. No. 5,264,018 to Koenigsberg et al. discloses a method for decontaminating soil by applying an oxygen delivery vehicle (i.e., oxygen release compounds; “ORC”) such as peroxides of calcium, potassium, or magnesium or mixtures thereof in an amount which increases the population of microorganisms in the soil that promote the biological degradation of environmental pollutants. The rate of liberation of oxygen from the ORC is controlled by adding a source of a simple phosphate (e.g., dihydrogen phosphate alkali metal salts, hydrogen phosphate alkali metal salts, urea phosphate, monoammonium phosphate, diammonium phosphate) into the aqueous phase during preparation of the metal peroxide to achieve the “intercalation” of the simple phosphates with the metal peroxides. The composition may additionally comprise a surfactant, macronutrients, micronutrients, or other beneficial additives for supplementing the nutrition and environment of the pollutant degrading microorganisms. Koenigsberg et al. do not disclose the use of complex phosphate compounds or other unique advantages of the present invention. Likewise, Koenigsberg et al. fail to acknowledge or disclose the use of the metallic peroxides to stimulate long-term, non-exothermic chemical-oxidation processes. Hence, Koenigsberg et al. do not disclose the present invention.
U.S. Pat. No. 5,866,003 to Okubo et al. discloses an apparatus for degrading environmental pollutants via aerobic bioremediation in-situ or ex-situ by supplying microorganisms and materials required by the microorganisms for degrading the pollutants. The materials supplied include oxygen release compounds including hydrogen peroxide and calcium peroxide as well as a nutrient supply. One benefit of this invention is that the oxygen is allowed to co-migrate downstream with the pollutant instead of supplying the oxygen to the microorganisms all at once. Likewise, the oxygen donors, nutrients and minerals are provided in the form of solids or semi-solids which can be further supplied as granules to provide for easy handling. Okubo et al. do not disclose the use of complex phosphate compounds or other unique advantages of the solid-chemical composition disclosed herein. Okubo et al. also fail to acknowledge or disclose the use of the solid- or semi-solid sources of active oxygen to stimulate long-term, non-exothermic, chemical-oxidation processes. Hence, Okubo et al. do not disclose the present invention.
U.S. Pat. No. 5,741,427 to Watts et al. discloses a method of treating contaminated soil and/or ground water comprising adding a source of an oxidizing agent, ligand donor, and a metal catalyst to the in-situ environment to promote and control the conversion of contaminants through the use of a chemical oxidation process. Sources of oxidizing agents include those that typically generate free radicals (e.g., calcium peroxide, sodium peroxide, ozone) and metal catalysts including metal salts, iron oxyhydroxides, iron chelates, and combinations thereof. This combination of oxidizing agents and metal catalysts promotes a Fenton's reaction in-situ. The composition is applied as a liquid through horizontal or vertical wells or infiltration trenches. Watts et al. fail to address the possible biological component of providing such oxygen donors to the environment. Watts et al. also do not disclose the use of complex phosphate compounds or other unique advantages of the solid-chemical composition disclosed herein. Hence, Watts et al. do not disclose the present invention.
U.S. Pat. No. 5,879,107 to Kiest et al. discloses a system and process for delivering fluids into subsurface contaminated soil and ground water to enhance in-situ microbial degradation of contaminants. The process uses a pattern of relatively closely spaced “vertical lancings” of the underground zone of contaminants dropped from the surface, using a high pressure low volume fluid infusion of a water slurry of time released oxygen compound providing chemicals and nutrients and/or microbes that biodegrade the pollutants. The fluid consists of a water slurry of magnesium peroxide with urea, ammonium phosphate, ammonium sulfate or a mono-potassium phosphate and/or organisms with attributes which can attack and break down the hydrocarbon pollutants into intermediate by-products and eventually into harmless carbon dioxide and water. Kiest et al. do not disclose the use of complex phosphate compounds as disclosed herein or other unique advantages of the solid-chemical composition disclosed herein. Likewise, Kiest et al. fail to acknowledge or disclose the use of the time-released oxygen sources to stimulate long-term, non-exothermic chemical-oxidation processes. Hence, Kiest et al. do not disclose the present invention.
U.S. Pat. No. 4,891,320 to Aust et al. discloses a process for degrading environmentally persistent organic pollutant compounds by reacting them with fungal enzymes containing a lignin-degrading enzyme (white rot fungi) and hydrogen peroxide. Aust et al. describe a preferred embodiment of the disclosed process whereby the addition of a living fungus, such as the white-rot fungus Phanerochaete chrysosporium, provides both the generation of both a lignin-degrading peroxidase enzyme and hydrogen peroxide, thereby avoiding the need to actually add the hydrogen peroxide. Aust et al. emphasize the importance of the non-specific lignin-degrading enzymes produced by white-rot fungi in degrading halogenated aromatic compounds such as PCBs, DDT and the like. Aust et al. also disclose in their process the importance of maintaining nutrient-nitrogen limited conditions to optimize the fungal-related biodegradation of such contaminants. Aust et al. do not disclose a solid-chemical composition which provides means for the chemical oxidation or aerobic bioremediation of contaminants nor do they disclose other unique advantages of the present invention. Aust et al. also do not disclose the use of a solid-chemical, sustained-release source of active oxygen to stimulate fungal biodegradation processes. Hence, Aust et al. do not disclose the present invention.
U.S. Pat. No. 5,476,788 to Lamar et al. discloses a solid-phase bioremediation method using naturally occurring lignin-degrading fungi. The method includes the use of an inoculum containing one or more lignin-degrading fungi and a lignocellulosic substrate, followed by a period of aerating and hydrating, to degrade contaminants to less toxic products. Lamar et al. specifically disclose the use of lignin-degrading fungal strains of Phanerochaete chrysosporium, Phanerochaete sordida, and Trametes hirsuta. Lamar et al. discuss the importance of fungal “lignin peroxidases or ligninases” in the biodegradation process. Lamar et al. specifically disclose the use of their process for the “in-place bioremediation” of halogenated hydrocarbons such as pentachlorophenol. Like Aust et al., Lamar et al. also disclose the importance of maintaining nutrient-nitrogen limited conditions to optimize the fungal-related biodegradation, and Lamar et al. present data which they appear to indicate that the addition of nutrient nitrogen in the form of potassium nitrate and ammonium chloride actually inhibits contaminant biodegradation. Lamar et al. do not disclose a solid-chemical composition which provides means for the chemical oxidation or aerobic bioremediation of contaminants, the use of a solid-chemical, sustained-release source of active oxygen to stimulate fungal biodegradation processes, nor do they disclose other unique advantages of the present invention. Hence, Lamar et al. do not disclose the present invention.
M. Arisoy (Bulletin of Environmental Contamination and Toxicology, 60: 872–876; 1998) describes the biodegradation of chlorinated organic compounds such as DDT, lindane and heptachlor by white-rot fungi including Phanerochaete chrysosporium, Pleurotus sajor-caju, Pleurotus florida, and Pleurotus eryngi. Arisoy reported that contaminant biodegradation was only observed as a co-metabolic process during what is termed a “secondary metabolism.” Arisoy, like Aust et al. and Lamar et al., noted that significant fungal contaminant biodegradation only occurred at high rates under nutrient-limited conditions. Arisoy does not disclose a solid-chemical composition which provides means for the chemical oxidation or aerobic bioremediation of contaminants does he disclose other unique advantages of the present invention. Hence, Arisoy does not disclose the present invention.